1. Field of the Invention
The present invention relates to a method for fractionating an oil or a fat to separate the high melting point components thereof.
2. Description of the Prior Art
It has been found useful to fractionate oils or fats to separate the high melting point components thereof to provide materials which are more useful than the original oils or fats for certain applications, such as the production of margarine.
A classical method for separating the high melting point components of an oil or fat by fractionation is known as "winterization." In this method, the oil or fat is melted, and then gradually cooled, and the crystals formed thereby are separated by filtration. The winterization method is the simplest fractionation method known in the prior art, but the process has certain inherent disadvantages. When an oil or fat is cooled, its viscosity increases, and oils adhere to the crystallized high melting point components. Moreover, the crystals formed in this method are of irregular sizes, and filtration of the crystallized components is therby rendered difficult.
In order to remove the adhered oils from the crystals formed in the winterization method, it is known to wash the crystals with detergents such as sodium lauryl sulfate. But usually the detergents contaminate the high melting point component fraction.
To avoid these disadvantages, solvent fractionation methods using organic solvents have been developed. However, the melting point of the liquid fraction is not as low in these methods, since the solvent does not dissolve a small portion of the high melting point components selectively. In addition, it is necessary to cool the micella to a quite low temperature to crystallize the high melting point components since their concentration in the solution is low. A further disadvantage of the solvent fractionation methods is that a solvent recovery process is required.
A need therefore continues to exist for a method for fractionating an oil or fat to separate high melting point components thereof by crystallization of the high melting components more quickly and in a more controlled crystalline form than in the winterization method, thereby permitting more rapid cooling and faster and more efficient filtration.